1. Technical Field
The present invention relates to a medical and surgical method and apparatus for the correction of injuries and disorders of the musculoskeletal system in general and contractures of joints in particular. More particularly this invention relates to a dynamic orthopedic device designed to increase the range of motion of joints suffering from contractures particularly the small joints of the hand.
2. Related Art
Skeletal joint contractures often result from trauma, including fractures and dislocations of joints. In addition, burns and their scar contracture reduce the range of motion of joints. Contractures also result from muscle imbalance across joints secondary to diseases such as leprosy. Dupuytren's disease commonly causes flexion contractures of the small joints of the hand. However, contractures can be flexion or extension contractures and can occur in any skeletal joint.
Traditionally, these injuries have been treated with various different modalities including splinting, serial plaster casts, and surgical release. Recently, significant innovations have resulted in more effective dynamic methods of treating such injuries in certain joints. For example, U.S. Pat. No. 5,376,091 to Hotchkiss et al., incorporated herein by reference, describes a dynamic finger joint support that has a proven clinical record of successful treatment of contractures. The Hotchkiss device is designed to allow, for example, the proximal interphalangeal (PIP) joint to be flexed and extended by a continuous passive motion machine that applies torque to the joint. Such flexion and extension is known to help overcome joint contractures so that the patient is often able to regain the full range of motion in the affected joint.
A deficiency of some prior art devices, generally referred to as hand splints, is that the torque required to increase the range of motion of the joint, can only be applied to the joint through the skin overlying the skeletal segments extending from either side of the joint. In addition, the force required to increase the range of motion of a joint needs to be applied for a significant amount of time. If the force is transmitted to the skeleton indirectly through the skin, the force compromises the circulation of the skin causing it to become tender, red and inflamed. In severe cases, particularly those with compromised sensation, ulcers may develop. As shown in FIGS. 1 and 2, the Hotchkiss device 5 avoids this problem for the distal interphalangeal (DIP) joint 10 by applying force directly to both the middle phalanx 12 and the distal phalanx 14. From the top view provided by FIG. 2, it is clear that pins 16, 18, 20, 22 are embedded in the skeletal elements through the lateral surface of the middle 12 and distal 14 phalanges.
Despite the successful clinical record of devices like Hotchkiss', there is room for improvement in the field. Many of the prior art devices and methods have potential problems and significant limitations that restrict their use in many applications. In particular, as shown in FIG. 2, Hotchkiss type devices 5 are required to be mounted on the lateral surface of the bones that extend from the contracted joint 10.
The Hotchkiss type device does not appear to be useable on metacarpal phalageal (MP) joints. In the case of the proximal interphalangeal (PIP) joint 24, for example, a Hotchkiss type device 5 appears to be most useful for the second and fifth PIP joints. However, because other fingers of the hand, including the webbing, would interfere with installation and use of the device on the third and fourth PIP joints, an alternate solution is required. Further, with regard to all of the PIP joints, there are soft tissues and tendons that glide along the lateral and medial surfaces of the phalanges, particularly the proximal phalanges of the fingers, that can be impaled by pins inserted into the sides of these phalanges, as required in Hotchkiss type devices used on the PIP joints. Additionally, installation of a Hotchkiss type device on the second and third DIP joints 10 would require the fingers to remain partially spread throughout the treatment period.
In light of such prior devices, what is needed is a means for biasing contracted joints that can be used on many different joints. What is further needed is a device that is not restricted to use only where it can be mounted on the lateral surface of the bones extending from a contracted joint. It would further be beneficial to identify a way to apply force directly to the skeleton without detrimentally disrupting soft tissue and tendons on the lateral surface of the bones extending from the joint. Such a device would preferably permit simultaneous treatment of adjacent joints.
In splinting techniques used in hand surgery and hand therapy, if a splint uses a single elastic element that crosses more than one joint to treat contracture of one or both joints, it is impossible to balance the torques applied to each of the joints. Thus, what is needed is a means to simultaneously apply independently controlled torque to multiple contracted joints that are adjacent along an appendage.